JP2590982B2 - Photomask manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to an improvement in a method of manufacturing a photomask, and aims at providing a method of manufacturing a photomask with a small amount of deflection which can be easily implemented. The step of depositing, the step of depositing a resist film on the surface of the light shielding film, and the deflection of the transparent substrate itself and the deflection of the transparent substrate caused by the stress of the light shielding film and the resist film. Applying a stressed thin film to the other surface of the transparent substrate.

[Industrial applications]

The present invention relates to a photomask, and more particularly to an improvement in a method for manufacturing a photomask.

2. Description of the Related Art The size of a dry plate in which a light-shielding film is applied to a transparent substrate such as a photomask or a reticle used for manufacturing a semiconductor device is increasing with the increase in the size of the substrate used for manufacturing the semiconductor device.

As a result, the amount of deflection of the transparent substrate increases, and the accuracy of the light-shielding pattern deteriorates.

Under the circumstances described above, there is a demand for a method of manufacturing a photomask with a small amount of deflection and high precision of a light shielding pattern.

[Conventional technology]

A conventional dry plate having a structure as shown in FIG. 4 is used.

A quartz glass is used as a transparent substrate 11a serving as a main body of the dry plate 11 shown in the drawing, and a thin film of a metal serving as a light shielding pattern 11b such as chrome is formed on the surface of the transparent substrate 11a. A resist film 11c specified by the user is applied to the surface, and is supplied from a trader in a dry state.

When the dry plate 11 delivered in such a shape is exposed using an exposure device in a mask process, the transparent substrate 11a is exposed.
Since the transparent substrate 11a is deformed due to the deflection, the accuracy of the exposed pattern is largely different between the central portion and the peripheral portion, and the deviation is large in the peripheral portion.

In the electron beam exposure apparatus, when exposing the pattern on the resist film 11c, the pattern is divided into regions called fields, and the exposure is performed. There is a gap between the joints of the field.

As a method for digitally grasping the displacement of the seam, there is a method using the Vernier principle disclosed in Japanese Patent Application Laid-Open No. 49-119584.

In this method, a vernier main scale and a vernier scale are formed at a distance corresponding to a field feed pitch, and a resist film 11 is formed.
This main scale and vernier scale are baked on c, and the amount of misalignment is measured by the opposing main scale and vernier scale.

[Problems to be solved by the invention]

The problem with the conventional dry plate described above is that the transparent substrate 11
The reason is that the transparent substrate 11a is largely bent by the contraction force of the light-shielding pattern 11b and the resist film 11c formed on the transparent substrate 11a.

According to the theoretical formula, the amount of deflection is 0.46 μm at the maximum for a transparent substrate 11a made of a 5-inch quartz glass plate, but is 0.55 μm at a maximum for a 6-inch quartz glass plate. Is formed, the amount of deflection is about 10 to 20 μm according to the measurement results.

When the dry plate 11 in such a state is used, it is impossible to manufacture a high-quality photomask or reticle having no deviation between fields.

An object of the present invention is to provide a method of manufacturing a photomask having a small amount of deflection, which can be easily performed in the above situation.

[Means for solving the problem]

The method for manufacturing a photomask of the present invention includes the steps of: applying a light-shielding film to one surface of a transparent substrate; applying a resist film to the surface of the light-shielding film; and bending the transparent substrate itself. And applying a thin film having a stress that cancels out the deflection of the transparent substrate caused by the stress of the light-shielding film and the resist film to another surface of the transparent substrate.

[Action]

That is, in the present invention, a light-shielding film is applied to one surface,
On the other surface of the transparent substrate having a resist film coated on the surface of the light-shielding film, a stress that offsets the deflection of the transparent substrate itself and the deflection of the transparent substrate caused by the stress of the light-shielding film and the resist film. Therefore, the deflection of the transparent substrate itself, the deflection of the transparent substrate caused by the stress of the light-shielding film and the resist film, and the deflection of the transparent substrate due to the stress of the thin film are balanced. Therefore, the deflection of the transparent substrate can be corrected, and a flat photomask can be manufactured.

〔Example〕

 An embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 1, the dry plate 1 of this embodiment is formed on a transparent substrate 1a made of a quartz glass plate having a thickness of 7 mm and a thickness of 3 mm.
A light-shielding film 1b made of chrome having a thickness of 1,000 mm is applied, and a resist film 1c having a thickness of 5,000 mm is further formed thereon, and a thin film for correcting the deflection of the transparent substrate 1a due to these, for example, as shown in the figure. A thin film 2 made of chromium having a thickness of 5,000 mm is formed on the surface on which the light shielding film 1b and the resist film 1c are not applied.

After exposing the resist film 1c of the dry plate 1 and before developing the resist film 1c, the thin film 2 is etched using an etching solution for the thin film 2.
Is removed by etching, and then development of the resist film 1c,
The photomask is completed by etching the light shielding film 1b.

In the case where the light-shielding film 1b and the thin film 2 can be etched by the same etching liquid as in the present embodiment, after the development of the resist film 1c, the etching of the light-shielding film 1b and the etching of the thin film 2 can be performed simultaneously. is there.

When the dry plate 1 having such a structure is compared with the dry plate 11 according to the prior art in which the thin film 2 is not formed, the third plate measured by a vernier as shown in FIG.
The values of the error at the position of the dry plate 1 shown in the figure are as shown in the table below.

Exposure equipment …… Electron beam exposure equipment Field dimensions …… 5mm square [Effects of the Invention] As is clear from the above description, according to the present invention, a light-shielding pattern of a transparent substrate and a surface on which a resist film is not applied are formed by forming a thin film to be applied very easily.
There is an advantage that it is possible to obtain a dry plate with a small amount of deflection and high precision, and an effect of remarkable quality improvement can be expected, which is extremely useful industrially.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment according to the present invention, FIG. 2 is a diagram showing an example of the relative positions of a main scale and a vernier of a vernier, FIG. FIG. 4 is a side sectional view showing a conventional dry plate. In the figure, 1 indicates a dry plate, 1a indicates a transparent substrate, 1b indicates a light-shielding film, 1c indicates a resist film, and 2 indicates a thin film.

Claims (1)

(57) [Claims] 1. A step of applying a light-shielding film to one surface of a transparent substrate, a step of applying a resist film to a surface of the light-shielding film, a deflection of the transparent substrate itself, the light-shielding film and the resist. Applying a thin film having a stress that offsets the deflection of the transparent substrate caused by the stress of the film to another surface of the transparent substrate.